Conversion of clarified hydrocarbon oil to distillate hydrocarbon fuel oil of low pour point in two catalytic stages



United States Patent Int. Cl. C10g 13/00 US. Cl. 208-60 7 Claims ABSTRACT OF THE DISCLOSURE Clarified or decant oil, from a catalytic cracking unit, which boils primarily above 650 F., is converted to distillate fuels, such as diesel or No. 2 fuel oil, of low sulfur content, low cloud point and low pour point by a twostage catalytic hydrocracking-hydroisomerization process. In the fisrt stage the clarified oil is contacted with hydrogen and a sulfur-resistant, non-precious metal hydrogenation catalyst, such as nickel-molybdenum or cobalt-molybdenum or an alumina or silica-almuina base catalyst, under hydrogenation or mild hydrocracking conditions at a temperature in the range of about 500 to 900 F. The product form the first stage is separated, such as by fractionation, to give a material boiling in the approximate 400-650 F. range which is contacted in a second stage with hydrogen and a platinum group metal-containing catalyst, such as a platinum on alumina-crystalline aluminosilicate catalyst, under hydroisomerization conditions at a temperature of about 450 to 800 F. It is preferable that the severity of the hydrocracking reaction be minimized and the hydroisomerization reaction be maximized in the second stage, such as by operating at a lower temperature in the second stage than in the first stage, to give a highly desirable distillate fuel oil product with enhanced low temperature flow characteristics.

In either or both stages, the oil and hydrogen can be passed over the catalysts in fixed beds or slurried with the catalysts to improve contact under reaction conditions. The first stage can be operated to give a yield of the fraction boiling in the approximate 400-650 F. range of at least 50 volume percent based on the clarified oil feed. Excellent yields of the desirable diesel or No. 2 fuel oil boiling about 400-650 F. with enhanced low temperature flow characteristics can be obtained, in up to 97% or more yields based on the feed to the second stage. The pour point of the 400-650 F. range fraction is lowered in the second stage by at least about 20 or 25 F., often to 0 F. and below. Diesel or No. 2 fuel oils can be obtained with cloud points as low as l5 F. and pour points as low as -20 F. and with sulfur content as low as .05 weight percent.

This invention relates to a two-stage catalytic process for upgrading clarified or decant hydrocarbon oil to fuel oil grade products. More particularly, this invention relates to a two-stage catalytic process for converting clarified hydrocarbon oil from a catalytic cracking unit to fuel oil grade products with enhanced low temperature flow characteristics, low sulfur content and improved burning qualities.

- It is an object of this invention to upgrade clarified or decant hydrocarbon oil to distillate fuel oil grade products, such as diesel and No. 2 fuel oil. A further object of this invention is to convert clarified oil from a catalytic cracking unit to distillate fuels of low sulfur content, low cloud point and low pour point. Other objects will appear hereinafter.

These objects are accomplished in accordance with the present invention by a two-stage catalytic process involv- 3,506,566 Patented Apr. 14, 1970 ing a combination of mild hydrocracking and hydroisomerization wherein heavy hydrocarbon oil components boiling primarily above 650 F. from a catalytic cracking unit, such as clarified or decant oil, are converted into distillate fuels, such as diesel fuel or No. 2 fuel oil grade products boiling in the range of about 400-650 F., with low sulfur content and enhanced low temperature flow characteristics, particularly low cloud point and low pour point. In the first stage the clarified oil is contacted with hydrogen and a sulfur-resistant, non-precious metal hydrogenation catalyst, such as nickel-molybdenum or cobalt-molybdenum on a silica-alumina or on an alumina base catalyst, under hydrogenation or mild hydrocracking-conditions at a temperature of about 500 to 900 F. The product from the first stage can contain dry gas, gasoline, a low sulfur fraction boiling in the range of most accepted diesel or No. 2 fuel oils or as a component of same, and an improved low sulfur content fraction suitable for feedstock to a catalytic cracking unit, or as a superior blending component for residual fuel. The product from the first stage is sent to a fractionating tower where any overhead product of C minus can be taken off, any C AOO EP gasoline can be withdrawn as a side stream, and a side stream boiling primarily in the range of about 400-650 F., preferably with at least about 25% weight boiling above about 550 F., i.e. in the about 550-650" F. range, is withdrawn and charged as feed to the second stage reactor. The pour point of this 400-650 F. fraction from the first stage, while lower than that of the clarified oil feed, is usually too high to be desirable for diesel or No. 2 fuel oils. There is also withdrawn from the fractionating tower a bottoms stream boiling above about 650 F. suitable for inclusion in feed to a catalytic cracking unit or for blending with other residual hydrocarbon mineral oil components.

The fraction boiling in the range of about 400 to 650 F. is contacted with hydrogen and a platinum group metal-containing hydroisomerization catalyst, such as a platinum or alumina-crystalline aluminosilicate catalyst, under hydroisomerization conditions at a temperature of about 450 to 800 F. The reaction conditions are preferably less severe in the second stage than in the first stage to minimize or decrease the hydrocracking reaction and to maximize or increase the hydroisomerization reaction. This is accomplished by selecting the operating conditions within the ranges set forth in the second stage, such as by employing a lower temperature in the second stage than in the first stage.

The clarified oil feedstock is contacted with hydrogen in the first stage of the present process in the presence of a non-precious metal hydrogenation catalyst at a temperature of about 500 to 900 F., preferably about 750 to 900 F. Other reaction conditions generally include pressures of about 300 to 2500 p.s.i.g. preferably about 500 to 1500 p.s.i.g.; weight hourly space velocities (WHSV) of about 0.25 to 10, preferably about 0.5 to 5; and hydrogen to feed oil ratios of about 1000 to 10,000, preferably about 2500 to 5000, s.c.f./b. It is preferred that the first stage be operated under reaction conditions that will give a first stage yield of the fraction in the approximate 400-650 F. boiling range of at least about 50 volume percent based on clarified oil feed. This can be accomplished by adjusting the operating conditions within the ranges herein set forth as is illustrated by the example.

The fraction boiling in the range of about 400 to 650 F. separated from the first stage product is employed as feed oil in a second stage where it is contacted with hydrogen in the presence of a platinum group metal-containing hydroisomerization-hydrocracking catalyst at a temperature of about 450 to 800 F., preferably about 550 to 700 F. The pressure employed in the second stage is often about 300 to 3000 p.s.i.g., preferably about 1500 to 2500 p.s.i.g. Weight hourly space velocities in the range of about 0.25 to 10, preferably 0.25 to 5, WHSV can be used in the second stage along with hydrogen rate of about 500 to 10,000, preferably about 1500 to 5000, s.c.f./b. of oil. It is preferable that the severity of the hydrocracking reaction be minimized and the hydroisomerization reaction be maximized in the second stage to give a product with low cloud point and low pour point and one that will fiow through a conduit at lower temperatures than the oil feedstock to the second stage. This is accomplished by adjusting the operating conditions within the ranges herein set forth such as by selecting a lower temperature in the second stage than in the first stage, particularly as specified in the preferred operating conditions.

In one embodiment of this invention, the clarified oil feedstock is passed with hydrogen through a fixed bed non-precious metal hydrogenation catalyst, such as a nickel-molybdenum or cobalt-molybdenum on a silicaalumina or on an alumina base catalyst, under the process conditions herein set forth in the first stage. The oil product from the first stage is fractionated and the 400- 650 F. range fraction is passed with hydrogen through a fixed bed platinum group metal-containing hydroisomerization-hydrocracking catalyst, such as a platinum or palladium on alumina catalyst fortified with a minor amount, such as about 2 to 25 weight percent of a crystalline aluminosilicate under the process conditions herein set forth in the second stage. The pour point of the 400- 650 F. range fraction is lowered in the second stage by at least about 20 or 25 F., often to F. and below. Often essentially all of this fuel oil product will flow at about --10 F. Excellent yields, often above 95%, of the diesel or fuel oil product having the desirable low cloud and low pour point are obtained in the second stage based on the 400-650 F. range fraction charged thereto.

In another embodiment of this invention a slurry system is employed to obtain intimate contact in a heterogeneous system composed of the clarified oil feedstock, a hydrogen rich gas and the solid non-precious metal hydrogenation catalyst. This embodiment can be effected, for example, by commingling the hydrogen rich gas and clarified oil feedstock, introducing the solid catalyst into the oil-hydrogen gas mixture, and heating to reaction temperature in a heater. Alternatively the oil-hydrogen gas mixture can be heated to reaction temperature and then the solid catalyst introduced. The hot, heterogeneous slurry of oil, catalyst, and hydrogen gas are then introduced to a soaking zone where the reaction is allowed to go to completion and where the catalyst will settle by gravity to the bottom of the soaking zone where it can be removed to be regenerated, slurried with fresh oil and returned to the System. The partially depleted hydrogen rich gas is withdrawn continuously from the top of the soaking zone, into a separating zone where any entrained oil is allowed to settle out. The gas from the separating zone may then be sent to an amine scrubber for removal of H 5 and then recompressed to operating pressure and returned to the system as recycle hydrogen gas. The decant oil is withdrawn from the soaking zone and passed through a filter to remove any entrained catalyst and then is passed to a fractionating zone where a 400-650 F. range fraction cut is obtained. This 400650 F. range fraction is passed to the second stage either over a fixed bed platinum group metal-containing catalyst as described in the first mentioned embodiment or is contacted in a'slurry with a hydrogen rich gas and the solid platinum group metal-containing catalyst and heated to reaction conditions as set forth in the second stage. The processing of the slurry in the second stage through a soaking zone, separating zone, withdrawal of decant oil from the soaking zone, passing through a filter to remove entrained catalyst, and then to a stripping or fractionating zone to remove light hydrocarbon fractions and to obtain the diesel or No. 2 fuel oil product can be similar in operation to that described for the first stage. A preferred size of catalyst particles in the slurry process embodiment is from about 0.014 to 0.028 inch or more in diameter. although this should not be construed to mean that such particles are necessarily spherical in shape.

Clarified oil is the bottoms derived from gasolineproducing catalytic cracking processes. The clarified oil may be the residual oil produced as a result of the cracking of suitable mineral oil cracking feedstocks such as gas oils in the presence of catalysts such as silica-alumina, crystalline aluminosilicate or other catalysts, usually silica-based cracking catalysts, which are frequently employed in the fluidized state. In distillation of the cracked oil, generally at about 7 to 25 p.s.i. pressure, to a maximum or end point of about 650 to 750 F., to obtain gasoline and gas oils overhead, there is produced a heavy residue or distillation bottoms containing entrained catalyst. To remove the catalyst, the residue is normally permitted to remain quiescent for a sufficient period of time to allow the catalyst particles to settle out, at which time the residual oil, substantially free of catalyst, may be decanted. In lieu of settling, the catalyst par ticles may be filtered or centrifuged from the oil, or such operations may be used in conjunction with settling.

In any case, there is obtained a bottoms or residual oil made by catalytic cracking of mineral oil and boiling primarily above 650 P. which is referred to in the art as clarified oil. Clarified oil boils primarily in the range of about 400 to 1000 F. and may have a 5 volume percent distillation point of at least about 500 F. or even at least about 600 F. and volume percent distillation point of at least about 800 F. with at least F. units or even at least about 200 F. units, separating the 5 percent distillation point and the 95 percent distillation point. The clarified oil feed is usually the full range clarified oil, that is, the entire bottoms obtained as aforementioned by the distillation of the oil from the cracking unit or it can be suitable bottoms fractions of the full range clarified oil, for example, a bottoms fraction having a 5 volume percent distillation point of below about 700 F. obtained, for instance, by vacuum distillation of the clarified oil usually to not less than about 50% bottoms. The clarified oil feed can have an API gravity preferably of up to about 25.

The catalyst used in the first stage of the present process can be any of the sulfur-resistant, non-precious metal hydrogenation catalysts, such as those conventionally employed in the hydrogenation of heavy petroleum oils. Examples of suitable catalyst ingredients are tin, vanadium, members of Group VI-B in the Periodic Table, i.e., chromium, molybdenum and tungsten, and metals of the iron group, i.e., iron, cobalt and nickel. Preferred catalysts in the first stage of the present process are nickel-molybdena or cobalt-molybdena. These metals are present in catalytically effective amounts, for instance about 2 to 30 weight percent, and may be present in the elemental form or in combined form such as the oxides or sulfides, the sulfide form being preferred. Mixtures of these materials or compounds of two or more of the oxides or sulfides can be employed, for example, mixtures or compounds of the iron group metal oxides or sulfides with the oxides or sulfides of Group VI-B metals constitute very satisfactory catalysts. Examples of such mixtures or compounds are nickel molybdate, tungstate or chromate (or thiomolybdate, thiotungstate 0r thiochromate) or mixtures of nickel or cobalt oxides with molybdenum, tungsten or chromium oxides. As the art is aware and as the specific example below illustrates, these catalystic ingredients are generally employed while disposed on a suitable carrier of the solid metal oxide type, e.g., apredominantly calcined or activated alumina or silicaalumina. Commonly employed catalysts have about 1 to 10% of an iron group metal and 5 to 25% of a Group VI-B metal (calculated as the oxide). Advantageously, the catalyst is nickel-molybdate supported on alumina or silica-alumina. Such preferred catalysts can be prepared by the method described in U.S. Patent 2,938,002, issued May 24, 1960 to Keith et al.

The platinum group metal-containing hydroisomerization-hydrocracking catalyst used in the second stage of the present invention contains a major amount of activated alumina and about 2 to 25, preferably about to 10, weight percent of a cation-exchanged crystalline aluminosilicate having a silica-to-alumina mole ratio greater than 2:1, preferably greater than 3:1; and a catalytic amount, say about 0.25 to 1, preferably about 0.5 to 0.8 weight percent of a platinum group metal.

The platinum group metals of the second stage catalyst include such Group VIII metals as, for example, platinum, palladium, rhodium or iridium. The platinum group metal may be present in the metallic form or as a sulfide, oxide or other combined form. The metal may interact with other constituents of the catalyst, but if during use the platinum group metal is present in the metallic form, then it is preferred that it be so finely divided that it is not detectable by X-ray diffraction means, i.e., that it exists as crystallites of less than about 50 A. in size. Of the platinum group metals, platinum and palladium are preferred. The catalyst of the first and second stages can be prereduced prior to use by heating in the presence of hydrogen, generally at temperatures of about 700 to 1100 F. The catalyst of the first stage is preferably presulfided as by contact with hydrogen sulfide at an elevated temperature.

The platinum group metal on alumina catalyst in the second stage is fortified with a minor amount of crystalline aluminosilicate; however, the support for the platinum group metal is usually composed predominantly of alumina of the activated or calcined type. This catalyst base is an activated or gamma-alumina such as those derived by calcination of amorphous hydrous alumina, alumina monohydrate, alumina trihydrate or their mixtures. The catalyst base precursor most advantageously is a mixture containing a major proportion of or predominating in, for instance about 65 to 95 weight percent of, one or more alumina trihydrates, bayerite, nordstrandite, or gibbsite, and about 5 to 35 weight percent of alumina monohydrate (boehmite), amorphous hydrous alumina or their mixture. The alumina base can contain small amounts of other solid oxides (such as kaolinite, montmorillonite, halloysite, etc.), titania, zirconia, etc., or their mixtures. The catalytic amount of platinum group metal on the alumina carrier usually falls within the range of about 0.01 to 2 weight percent, often about 0.1 to 1 weight percent based on the total catalyst.

The crystalline aluminosilicate component of the second stage catalyst may be synthetic or naturally-occurring faujasite and has a pore size of about 8 to 15 A., preferably about 10 to 14 A. Usually, with a given material, the pores are relatively uniform in size and often the crystalline aluminosilicate particles are primarily less than about 15 microns in size, preferably less than about 10 microns. In the crystalline aluminosilicate the silica-toalumina mole ratio is greater than 2:1 or even greater than 3:1 and is usually not above about 12: 1, preferably being about 4 to 6:1. The aluminosilicate is at least about 50%, preferably at least about 75%, hydrogen or polyvalent metal exchanged, that is, at least about 50% of the metal cations present in the aluminosilicate are replaced by hydrogen or polyvalent metal or combinations thereof. Exchange is commonly carried out by exchange of the sodium cations of the synthetic or naturally-occurring aluminosilicates with ammonium or metal cations, for instance through contact with an aqueous solution of a chloride or other water-soluble compound and subsequently calcining the aluminosilicate.

One method of preparing the second stage catalyst is by combining an alumina hydrogel and the exchanged crystalline aluminosilicate and drying the mixture, for instance at temperatures of about 230 to 600 F. The crystalline aluminosilicate may, if desired, be exchanged after it is combined with the alumina. The dried material can be calcined, for instance, at a temperature of the order of about 700 to 1500 F., preferably about 800 to 1100 F. The platinum group metal may be added before or after the calcination, for example, by ion exchange or impregnation. In any event, after the platinum group metal is added, the catalyst is dehydrated and acticated at the calcination temperature described above. An available method for adding the platinum group metal by ion-exchange comprises treating the alumina-crystalline aluminosilicate mixture with an aqueous solution containing complex water-soluble, metal-amine cations, both organic and inorganic, of the metal to be deposited in the crystal structure. These complex cations ion-exchange with the cations present in the crystalline aluminosilicate. The exchanged material is then removed from the s0lution, dried and activated or calcined, for example, by heating the material up to a temperature of about 250 C. in a flowing stream of inert dry gas or vacuum. The activation may be effected at a temperature below the temperature at which the complex cations are destroyed. The activated material may then be subjected to heat treatment at a temperature not exceeding about 650 C. and

preferably not exceeding about 500 C. in vacuum or inert atmosphere whereby the complex cation is destroyed and the metal is reduced in the material. Should the thermal treatment be insufficient to reduce the metal of the complex cations to the elemental state, chemical reduction either alone or in combination with thermal reduction may be employed. Throughout the operation excessive temperatures and extremes of acidity are to be avoided since they may tend to destroy the crystal structure of the crystalline aluminosilicate mixture.

The platinum group metal may also be added by impregnation. The alumina-crystalline aluminosilicate mixture, for example, either with or without previous evacuation, may be soaked in either a dilute or concentrated solution, usually aqueous chloroplatinic acid, ammonium hexathiocyanaplatinate (IV) or hexathiocyanate platinic acid, often in an amount just sufiicient to wet the material and be completely absorbed. Also, if desired, the solution may be incorporated into the alumina-crystalline aluminosilicate during the formation of the latter.

Either before or after dehydration, the catalyst can, if desired, be formed into macrosized particles by tabletting or extruding. Generally, these particles are about to /2" in diameter and about to 1" or more in length. Although these macrosized particles are usually formed after dehydration and before calcination, this, of course, is optional and can be done at any time found most convenient.

The process of the present invention is illustrated by the following example which exemplifies a preferred embodiment of the invention.

EXAMPLE A clarified oil from a fluid catalytic cracking unit, having the properties set forth in Table 1 below, is employed as the feedstock.

Table 1 API gravity 14.0 Sulfur percent 0.785 Pour point F IBP F 580 5% F 650 10% F 696 50% F 785 70% F 830 95% F 894 Viscosity at F. cs 14.5

This clarified oil feedstock is contacted in a first stage reactor with hydrogen in the presence of a nickel-molyb- 7 denum on alumina catalyst at a temperature of 875 F. under a pressure of 1000 p.s.i.g., at a weight hourly space velocity of 1.0 and at a hydrogen rate of 5000 s.c.f./b. of oil.

The product from this first stage is fractionated and the yields are set forth in Table 2.

Table 2 Gas (C minus), wt. percent 3.6 C 400 EP gasoline, vol. percent 4.9 400650 F. diesel cut, vol. percent 54.9 650+, vol. percent 41.6

The 400650 F. diesel cut fraction had a cloud point of +250 F., a pour point of +20 F., and a sulfur content of 0.12 weight percent.

This 400650 F. diesel cut fraction is contacted in a second stage reactor with hydrogen in the presence of a platinum-containing alumina-crystalline aluminosilicate catalyst. The catalyst contains about 0.7 weight percent platinum and about 7 weight percent of an about 90% hydrogen-exchanged crystalline aluminosilicate molecular sieve having a pore size of about 13 A. and a silica-toalumina mole ratio of about 4 to 1. The 400650 F. diesel cut fraction is contacted in the second stage reactor with hydrogen in the presence of the platinum-containing alumina-crystalline aluminosilicate catalyst at a temperature of 550 F. under a pressure of 2000 p.s.i.g., at a weight hourly space velocity of 0.5 and at a hydrogen rate of 2500 s.c.f./ b. of diesel cut fraction feed.

The composition of the resulting products are set forth in Table 3 below.

The 400650 F. bottoms product from fractionation of the second stage products has a cloud point of l5 F., a pour point of 20 F. and a sulfur content of 0.05 weight percent.

This example shows that in the first stage about 55% of 400650 F. diesel cut is obtained from clarified oil having an initial boiling point of 580 F., having 95% of its components boiling above 650 F., and having a pour point of +95 F. However this 400650 F. diesel cut from the first stage has a cloud point of +25 F. and a pour point of +20 F. which is too high to be desirable. The processing of this diesel cut in the second stage reduces the cloud point to 15 F. and the pour point to F. which is very desirable for a commercial product. Furthermore the sulfur content is reduced from 0.12 to .05 weight percent in the second stage. There is also obtained in the second stage a small amount, 2.4% of lighter product boiling below 400 F. The 97.6% yield from the second stage of 400650 F. diesel bottoms product with the very desirable low cloud point and pour point is excellent.

It is claimed:

1. A catalytic process for converting clarified hydrocarbon oil boiling primarily above 650 F. to distillate hydrocarbon fuel oil of low pour point, which comprises contacting in a first stage the clarified hydrocarbon oil with hydrogen and a non-precious metal hydrogenation catalyst under hydrogenation conditions sufficient to give a product containing a fraction of high pour point, boiling primarily in the range of about 400650 F., and in an amount of at least about 50 volume percent based on the clarified oil, the hydrogenation conditions in said first stage being at a temperature in the range of about 500 to 900 F., a pressure of about 300 to 2500 p.s.i.g., a weight hourly space velocity of about 0.25 to 10 and a hydrogen rate of about 1000 to 10,000 s.c.f./b. of clarified oil, separating a fraction boiling primarily in the range of about 400650 F. from the first stage product, contacting in a second stage, said separated fraction of high pour point boiling primarily in the range of about 400 650 F. with hydrogen and a platinum group metal-containing catalyst under hydroisomerization conditions sufficient to lower the pour point of the fraction boiling primarily in the range of about 400650 F. by at least about 20 F. to below about 0 F. and to minimize hydrocracking so as to obtain as a product a yield above about based on the oil charge to the second stage, of a distillate hydrocarbon fuel oil boiling primarily in the range of about 400650 F. and having a pour point below 0 F. and at least about 20 F. lower than that of the corresponding fraction from the first stage, the hydroisomerization conditions in said second stage being at a lower temperature than in the first stage and in the range of about 450 to 800 F., a pressure of about 300 to 3000 p.s.i.g., a weight hourly space velocity of about 0.25 to 10 and a hydrogen rate of about 500 to 10,000 s.c.f./ b. of oil charge to the second stage.

2. A catalytic process for converting clarified hydrocarbon oil to distillate hydrocarbon fuel oil of low pour point as set forth in claim 1, wherein the hydrogenation catalyst in the first stage comprises an iron group metal and a Group VL-B metal.

3. A catalytic process for converting clarified hydrocarbon oil to distillate hydrocarbon fuel oil of low pour point as set forth in claim 1, wherein the hydrogenation catalyst in the first stage is selected from the group consisting of nickel-molybdenum and cobalt-molybdenum on alumina or silica-alumina base.

4. A catalytic process for converting clarified hydrocarbon oil to distillate hydrocarbon fuel oil of low pour point as set forth in claim 1, wherein the platinum group metal-containing catalyst is a platinum on alumina-crystallin aluminosilicate catalyst, said crystalline aluminosilicate having pore sizes in the range of about 8 to 15 A.

5. A catalytic process for converting clarified hydrocarbon oil from a fluid catalytic cracking unit, boiling primarily above 650 F., to distillate hydrocarbon fuel oil of low pour point, which comprises contacting in a first stage clarified hydrocarbon oil with hydrogen and a hydrogenation catalyst selected from the group consisting of nickel molybdenum and cobalt-molybdenum on alumina or silica-alumina base, under hydrogenation conditions sufiicient to give a. product containing a fraction of high pour point, boiling primarily in the range of about 400 650 F., and in an amount of at least about 50 volume percent based on the clarified oil, the hydrogenation conditions in said first stage being at a temperature in the range of about 750 to 900 F., a pressure of about 500 to 1500 p.s.i.g., a weight hourly space velocity of about 0.5 to 5, and a hydrogen rate of about 2,500 to 5,000 s.c.f./b. of clarified oil, fractionating the product from the first stage and separating a fraction boiling primarily in the range of about 400650 F., contacting in a second stage said separated fraction of high pour point boiling primarily in the range of about 400650 F. with hydrogen and a catalyst comprising a platinum group metal on alumina-crystalline aluminosilicate having pores in the 8 to 15 A. range, under hydroisomerization conditions sufiicient to lower the pour point of the fraction boiling primarily in the range of about 400650 F. by at least about 20 F. to below about 0 F. and to minimize hydrocracking so as to obtain as a product a yield above about 95 F. based on the oil charge to the second stage, of a distillate hydrocarbon fuel oil boiling primarily in the range of about 400650 F. and having a pour point below 0 F. and at least about 20 F. lower than that of the corresponding fraction from the first stage, the hydroisomerization conditions in said second stage being at a temperature in the range of about 550 to 700 F., a pressure of about 1500 to 2500 p.s.i.g., a weight hourly space velocity of about 0.25 to 5, and a hydrogen rate of about 1,500 to 5,000 s.c.f./b. of oil charge to the second stage.

6. A catalytic process for converting clarified hydrocarbon oil from a fluid catalytic cracking unit, boiling primarily above 650 F., to distillate hydrocarbon fuel oil of low pour point as set forth in claim 5, wherein the hydrogenation catalyst in the first stage is nickel molybdenum on alumina and the hydroisomerization catalyst in the second stage is platinum on alumina-crystalline aluminosilicate having pores in the 10 to 14 A. range.

7. A catalytic process for converting clarified hydrocarbon oil from a fluid catalytic cracking unit, boiling primarily above 650 F., to distillate hydrocarbon fuel oil of low pour point, which comprises contacting in a first stage the clarified hydrocarbon oil with hydrogen and a nickelmolybdenum on alumina catalyst under hydrogenation conditions sufficient to give a product containing a fraction of high pour point boiling primarily in the range of about 400650 F., and in amount of at least about 50 volume percent based on the clarified oil, the hydrogenation conditions in said first stage being at a temperature of 875 F. under a pressure of 1000 p.s.i.g., at a weight hourly space velocity of 1, and a hydrogen rate of 5000 s.c.f./ b. of clarified oil, fractionating the product from the first stage and separating a fraction boiling primarily in the range of about 400-650 F., contacting in a second stage said separated fraction of high pour point boiling primarily in the range of about 400650 F. with hydrogen and a platinum-on-alumina-crystalline aluminosilicate catalyst having pores in the 10 to 14 A. range, under hydroisomerization conditions sufficient to lower the pour point of the fraction boiling primarily in the range of about 400- 650 F. by at least about 20 F. to below 0 F. and to minimize hydrocracking so as to obtain as a product a yield above about 95%, based on the oil charge to the second stage, of a distillate hydrocarbon fuel oil boiling primarily in the range of about 400650 F. and having a pour point below 0 F. and at least about 20 F. lower than that of the corresponding fraction from the first stage, the hydroisomerization conditions in said second stage being at a temperature of 550 F. under a pressure of 2000 p.s.i.g., at a weight hourly space velocity of 0.5 and at a hydrogen rate of 2500 s.c.f./b. of oil charge to the second stage.

' References Cited UNITED STATES PATENTS 3,140,253 7/1964 Plank et al 208120 3,184,402 5/ 1965 Kozlowski et a1. 20859 3,254,017 5/1'966 Arey et al. 20859 DELBERT E. GANTZ, Primary Examiner ABRAHAM RIMENS, Assistant Examiner U.S. c1. X.R. 208-49, 111, 112 

